Method for interconnecting anodes and cathodes in a flat capacitor

ABSTRACT

In one aspect, a method of interconnecting two or more foils of a capacitor, the method comprising connecting together one or more anode connection members of one or more anode foils and one or more cathode connection members of one or more cathode foils and electrically isolating the one or more anode foils from the one or more cathode foils.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a division of U.S. application Ser. No.10/299,234, filed on Nov. 19, 2002, which is a division of U.S.application Ser. No. 09/706,519, filed on Nov. 3, 2000, now issued asU.S. Pat. No. 6,509,588, the specifications of which are herebyincorporated by reference.

[0002] This application is related to application Ser. No. 09/706,447,filed on Nov. 3, 2000, now issued as U.S. Pat. No. 6,699,267, thespecification of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[0003] The present invention concerns implantable medical devices, suchas defibrillators and cardioverters, particularly structures and methodsfor capacitors in such devices.

BACKGROUND

[0004] Capacitors have undergone substantial improvement over the years.Smaller capacitors are in demand for various applications. One suchapplication is for biomedical implants. For example, defibrillators andpacemakers use capacitors for pulse delivery.

[0005] The defibrillator or cardioverter includes a set of electricalleads, which extend from a sealed housing into the walls of a heartafter implantation. Within the housing are a battery for supplyingpower, monitoring circuitry for detecting abnormal heart rhythms, and acapacitor for delivering bursts of electric current through the leads tothe heart.

[0006] The capacitor can take the form of a flat aluminum electrolyticcapacitor. Flat capacitors include a stack of flat capacitor elementsmounted within a capacitor case. Each flat capacitor element includesone or more separators between two sheets of aluminum foil. One of thealuminum foils serves as a cathode (negative) foil, and the other servesas an anode (positive) foil. The capacitor elements each have anindividual capacitance (or energy-storage capacity) proportional to thesurface area of the foil.

[0007] One drawback in manufacturing such capacitors is that each of theanodes and each of the cathodes must be connected together. Forinstance, all the anodes are crimped or welded together and attached toa feedthrough terminal for connection to circuitry outside the capacitorcase. Another process is also done for the cathode foils in thecapacitor stack. Errors during the manufacturing steps may cause defectsin the capacitor or decrease the reliability of the capacitor after itis constructed. Another drawback is that the interconnections take upspace within the capacitor. This increases the size of the capacitor,which is undesirable when the capacitors are used for implantablemedical devices such as defibrillators.

[0008] Thus, what is needed is a simple way to provide the anode andcathode interconnections of capacitors with as few steps as possible andwhich lends itself to mass producing said capacitors.

SUMMARY

[0009] To address these and other needs, interconnection structures andmethods for flat capacitors have been devised. In one embodiment, amethod includes connecting together one or more anode connection membersof one or more anode foils and one or more cathode connection members ofone or more cathode foils and electrically isolating the one or moreanode foils from the one or more cathode foils. Among other advantages,the method reduces the processing steps for interconnecting the foils ofa capacitor, and provides a capacitor having a smaller amount of roomtaken up by its interconnections.

[0010] In one aspect, a capacitor having a first anode layer, a secondanode layer, a cathode layer between the first anode layer and thesecond anode layer, a first separator layer between the first anodelayer and the cathode layer, a second separator layer between the secondanode layer and the cathode layer; and a conductive interconnect betweenthe first anode layer and the second anode layer, the conductiveinterconnect passing through a cathode hole in the cathode; wherein theconductive interconnect has a cross section which is smaller than thecathode hole and the conductive interconnect is placed to avoid directelectrical contact with the cathode layer and wherein the first anodeand the second anode are electrically connected through the conductiveinterconnect.

[0011] Another aspect of the present invention includes variousimplantable medical devices, such as pacemakers, defibrillators, andcardioverters, incorporating one or more capacitors having one or moreof the novel features described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is an isometric view of a flat capacitor according to oneembodiment of the present invention.

[0013]FIG. 2A is a top view of an anode foil for use in constructing acapacitor according to one embodiment of the present invention.

[0014]FIG. 2B is a top view of a cathode foil for use in constructing acapacitor according to one embodiment of the present invention.

[0015]FIG. 3A is a top view of an anode foil for use in constructing acapacitor according to one embodiment of the present invention.

[0016]FIG. 3B is a top view of a cathode foil for use in constructing acapacitor according to one embodiment of the present invention.

[0017]FIG. 4 is a perspective view of a stack of one or more anodes andcathodes of FIGS. 2A and 2B.

[0018]FIG. 5 is a perspective view of the stack of FIG. 4 after thestack has been processed according to one embodiment of the presentinvention.

[0019]FIG. 6 is a flowchart depicting a method of interconnecting anodesand cathode foils of a capacitor according to one embodiment of thepresent invention.

[0020]FIG. 7 shows a top view of a capacitor stack according to oneembodiment.

[0021]FIG. 8 shows a cross-section of a portion of FIG. 7.

[0022]FIG. 9 shows a partially etched anode foil according to oneembodiment.

[0023]FIG. 10 shows a side view of a foil having masks according to oneembodiment.

[0024]FIG. 11 show a top view of FIG. 10.

[0025]FIG. 12 shows a method according to one embodiment.

[0026]FIG. 13 is a block diagram of a generic implantable medical deviceincluding a capacitor according to one embodiment of the presentinvention.

DETAILED DESCRIPTION

[0027] The following detailed description, which references andincorporates the figures, describes and illustrates one or more specificembodiments of the invention. These embodiments, offered not to limitbut only to exemplify and teach the invention, are shown and describedin sufficient detail to enable those skilled in the art to practice theinvention. Thus, where appropriate to avoid obscuring the invention, thedescription may omit certain information known to those of skill in theart.

[0028]FIG. 1 shows a flat capacitor 100 constructed according to oneembodiment of the present invention. Although capacitor 100 is aD-shaped capacitor, in other embodiments, the capacitor is anotherdesirable shape, including, but not limited to rectangular, circular,oval or other symmetrical or asymmetrical shape. Capacitor 100 includesa case 101 which contains a capacitor stack 102. In the exemplaryembodiment, case 101 is manufactured from a conductive material, such asaluminum. In other embodiments, the case is manufactured using anonconductive material, such as a ceramic or a plastic.

[0029] Capacitor 100 includes a first terminal 103 and a second terminal104 for connecting capacitor stack 102 to an outside electricalcomponent, such as heart monitor circuitry, including defibrillator,cardioverter, and pacemaker circuitry. In the exemplary embodiment,terminal 103 is a feedthrough terminal insulated from case 101, whileterminal 104 is directly connected to case 101. In other embodiments,the capacitor incorporates other connection methods, depending on otherdesign factors. For instance, in some embodiments, capacitor 100includes two or more feedthrough terminals 103.

[0030] Capacitor stack 102 includes capacitor elements 105 a, 105 b, 105c, . . . , 105 n, with each capacitor element 105 a-105 n including oneor more cathodes, anodes, and separators. Each cathode is a foilstructure and can include aluminum, tantalum, hafnium, niobium,titanium, zirconium, and combinations of these metals. In oneembodiment, each cathode of capacitor stack 102 is connected to theother cathodes by welding or other connection methods which will bediscussed below. The cathodes are coupled to conductive case 101, andterminal 104 is attached to case 101 to provide a cathode connection tooutside circuitry. In some embodiments, the cathode is coupled to afeedthrough conductor extending through a feedthrough hole.

[0031] The separator is located between each anode and cathode. In oneembodiment, the separator includes one or more sheets of kraft paperimpregnated with an electrolyte. In one embodiment, the separatorincludes two sheets of paper. The electrolyte can be any suitableelectrolyte for an electrolytic capacitor, such as an ethylene-glycolbase combined with polyphosphates, ammonium pentaborate, and/or anadipic acid solute.

[0032] In one embodiment, one or more of the anodes of capacitor stack102 is a multi-anode stack which includes three foil layers. In otherembodiments, one or more anode stacks include one, two, three or moreanode foils having a variety of anode shapes. The anode foils aregenerally foil structures and can include aluminum, tantalum, hafnium,niobium, titanium, zirconium, and combinations of these metals. In oneembodiment, at least portions of a major surface of each anode foil isroughened or etched to increase its effective surface area. Thisincreases the capacitive effect of the foil with no relative increase involume. Other embodiments incorporate other foil compositions and/orclasses of foil compositions.

[0033] In one embodiment, each anode is connected to the other anodes ofthe capacitor and coupled to feedthrough assembly 103 for electricallyconnecting the anode to circuitry outside the case. In some embodiments,the anodes are connected to the case and the cathodes are coupled to afeedthrough assembly. In other embodiments, both the anode and thecathode are connected to feedthroughs.

[0034]FIG. 2A shows an anode 202 according to one embodiment of thepresent invention. Anode 202 is shown before it is assembled intocapacitor stack 102 as shown in FIG. 1. Anode 202 includes a main bodyportion 204 having one or more connection members 206. In oneembodiment, connection member 206 includes one or more separate membersattached to the anode by welding, staking, or other connection method.

[0035] In other embodiments, connection member 206 is an integralportion of anode 202, and is punched, laser-cut, or otherwise shapedfrom the anode foil. In such an embodiment, portions of connectionmember 206 are not etched along with the rest of anode 202. Forinstance, a chemical mask is put on portions of connection member 206 tokeep those masked portions from becoming etched during the etchingprocess. As will be discussed below, this provides that those unetched,non-porous sections make welding the edges of the anodes to each othereasier.

[0036] Connection member 206 includes a proximal section 208 and distalsection 210. In the embodiment of FIG. 2A, connection member 206 is anL-shaped member. However, it can also be hook shaped, U-shaped, and/orhave other shape. In one embodiment, a portion of a distal section 210along its outer edge is unetched, as discussed above.

[0037] In one embodiment, proximal section 208 is connected to main body204 and is defined in part by a pair of cut-out portions 212 and 214located on opposing sides of proximal section 208. Distal section 210 isconnected to a portion of proximal section 208. In one embodiment, it isintegral with proximal section 208. In some embodiments, distal section210 is attached as a separate member. In one embodiment, distal section210 is defined in part by a cut-out portion 216 which is located betweenmain body 204 and distal section 210, and a cut-out portion 218 whichseparates distal section 210 from main body 204.

[0038] In this embodiment, connection member 206 is located within thegeneral perimeter or outline of anode 202. In other embodiments,connection member extends further from the main body of anode 202 orconnection member 206 is more internal within the main body of anode202.

[0039] In some embodiments, each anode foil in capacitor stack 102includes an connection member such as connection member 206. In otherembodiments, one or more anode foils in a multi-anode stack have aconnection member 206 while the other anode foils in the multi-anodestack are connected to the anode having the connection member. Forinstance, in one embodiment, a three-foil anode stack includes one foilhaving an connection member 206 and two foils without connectionmembers. The two foils without connection members are welded, staked, orotherwise attached to the foil having the connection member.

[0040]FIG. 2B shows a cathode 302 according to one embodiment of thepresent invention. Cathode 302 is shown before it is assembled intocapacitor stack 102 as shown in FIG. 1. Cathode 302 includes a main bodyportion 304 having one or more connection members 306. In oneembodiment, connection member 306 is an integral portion of cathode 302,and is punched, laser-cut, or otherwise shaped from the anode foil. Inone embodiment, connection member 306 includes one or more separatemembers attached to the anode by welding, staking, or other connectionmethod.

[0041] In one embodiment, connection member 306 includes a proximalsection 308 and a distal section 310. In the embodiment of FIG. 2B,connection member 306 is an L-shaped member. However, in someembodiments it is hook shaped, U-shaped, and/or have other shape.

[0042] In one embodiment, proximal section 308 is connected to main body304 and is defined in part by a pair of cut-out portions 312 and 314located on opposing sides of proximal section 308. Distal section 310 isconnected to a portion of proximal section 308. In one embodiment, it isintegral with proximal section 308. In some embodiments, distal section310 is attached as a separate member. In one embodiment, distal section310 is defined in part by a cut-out portion 316 which is located betweenmain body 304 and distal section 310, and a cut-out portion 318 whichseparates distal section 310 from main body 304.

[0043] In this embodiment, connection member 306 is located within thegeneral perimeter or outline of cathode 302. In other embodiments,connection member 306 extends further from the main body of cathode 302or connection member 306 is more internal within the main body ofcathode 302.

[0044]FIGS. 3A and 3B show an anode 202′ and a cathode 302′ according toone embodiment of the present invention. Anode 202′ and cathode 302′ areshown before it is assembled into capacitor stack 102 as shown inFIG. 1. Anode 202′ and cathode 302′ are generally similar to anode 202and cathode 302, respectively, except connection member 206′ does notinclude a cut-out such as cut-out 212 of anode 202 and connection member306′ does not include a cut-out such as cut-out 318 of cathode 302.Other embodiments utilize other shapes and locations for connectionmembers such as connection members 206, 206′, 306, and 306′,

[0045] For instance, in various embodiments, connection members 206 and306 may be in different positions along the edges or even within themain body portions of the capacitor foils 202 and 302. For instance, insome embodiments connection members 206 and 306 are located along edges220 and 320 of the respective foils 202 and 302. In some embodiments,the portions are located along curved edges 222 and 322 of therespective foils 202 and 302. In other embodiments, the portions may becut-out within main bodies 204 and 304.

[0046] In one embodiment, proximal section 308 of cathode 302 andproximal section 208 of anode 202 are located in different positions(relative to each other) on their respective foils, while distalsections 210 and 310 are generally commonly positioned. For instance, inone embodiment connection members 206 and 306 of the anode 202 and thecathode 302, respectively, are mirror images of each other. In someembodiments, connection members 206 and 306 have generally reverseimages of each other.

[0047]FIG. 4 shows a stack 402 of one or more alternating anodes 202 andcathodes 302. As shown in FIG. 4, connection members 206 and 306 areoverlaying and underlying each other. As used herein, overlay andunderlay refer to the position or location of portions of the foilswhich are commonly positioned from a top view. In the embodiment of FIG.4, it is seen that connection members 206 and 306 have some commonlypositioned portions relative to each other and some portions which areexclusively positioned relative to each other.

[0048] For instance, proximal sections 208 of anodes 202 are exclusivelypositioned or located. This means that at least a portion of proximalsections 208 do not overlay or underlay a portion of cathodes 203.Likewise, proximal sections 308 of cathodes 302 are exclusive portionsand include at least a portion not overlaying or underlaying a portionof anode 202. Conversely, distal sections 210 and 310 are commonlypositioned and each include at least a portion overlaying or underlayingeach another. Cut-out portions 214 and 314 are also commonly positioned.Cut-out 218 is commonly positioned with cut-out 312 while cut-out 212 iscommonly positioned with cut-out 318.

[0049] When stacked as shown in FIG. 4, the edges of distal sections 210and 310 form a surface 410. In this embodiment, surface 410 cangenerally be described as having a first portion 410 a which fronts theproximal sections 208 of anodes 202, a second portion 410 b which frontscommon cut-portions 214 and 314, and third portion 410 c which frontsthe proximal sections 308 of cathodes 302.

[0050] In this embodiment, distal sections 210 and 310 of anodeconnection member 206 and cathode connection member 306 are fullyoverlaying one another. Fully overlaying means that there are generallyno gaps along surface 410 of stack 402 when the anodes and cathodes arestacked as in FIG. 4. The fully overlayed structure of stack 402provides a complete surface 410 which provides for ease of edge-weldingor otherwise connecting connection members 206 and 306 together, as willbe described below. Other embodiments leave one or more gaps in surface410 when the anodes and cathodes are stacked. For instance, in someembodiments, one or more of distal sections 210 or 310 may not reach allthe way across front surface 410.

[0051] After being stacked as discussed above, at least portions ofconnection members 206 and 306 are connected to each other. Forinstance, in one embodiment portions of distal sections 210 and 310 areconnected to each other. In one embodiment, distal sections 210 and 310are edge-welded all along surface 410. In one embodiment, distalsections 210 and 310 are only connected along portion 410 a and 410 c ofsurface 410. In one embodiment, distal sections 210 and 310 are solderedalong surface 410. In some embodiments, portions of distal sections 310and 210 are staked, swaged, laser-welded, or connected by anelectrically conductive adhesive. In other embodiments, portions ofproximal sections 208 are connected to each other and/or portions ofproximal sections 308 are connected to each other.

[0052] After being connected, portions of connection members 206 and 306are removed or separated so that proximal sections 208 and 308 areelectrically isolated from each other. As used herein, electricallyisolated means that sections 208 and 308 are electrically insulated fromeach other at least up to a surge voltage of capacitor 100.

[0053]FIG. 5 shows stack 402 after portions of distal sections 210 and310 have been removed from the stack, forming a separation 502 betweenanode connection members 206, which together comprise anode connectionsection 508, and cathode connection members 306, which together comprisecathode connection section 510. Separation 502 in the present embodimentelectrically isolates section 508 from section 510. Proximal sections308 are still coupled to each other as are proximal sections 208. Insome embodiments, separation 502 is a thin slice. In some embodiments,separation 502 is as wide as cut-outs 214 and 314, as shown in FIG. 5.In some embodiments, an electrically insulative material is inserted inseparation 502. In various embodiments, separation 502 is formed bylaser cutting, punching, and/or tool or machine cutting.

[0054]FIG. 6 shows a flowchart depicting a method 600 forinterconnecting two or more foils of a capacitor according to oneembodiment of the present invention. Method 600 includes a block 602,positioning the connection members of two or more foils, a block 604,connecting the connection members, and block 606, electrically isolatingportions of the connection members from each other.

[0055] In one embodiment, block 602, positioning the connection membersof two or more foils, includes stacking an anode foil having aconnection member having a proximal section and a distal section upon acathode foil having a connection member having a proximal section and adistal section. The foils and connection members are positioned so thatthe proximal section of the anode foil connection member does notoverlay the proximal section of the cathode foil connection member andthe distal section of the anode foil connection member at leastpartially overlays the distal section of the cathode foil connectionmember.

[0056] In one embodiment, block 604, connecting the connection members,includes connecting the connection member of the anode foil to theconnection member of the cathode foil. In one embodiment, this includesconnecting the distal section of the anode connection member and thedistal section of the cathode connection member at a portion of theanode connection member that overlays (or underlays) the portion of thecathode connection member. In one embodiment, connecting comprises asingle, continuous connection process. For instance, a laser weld orstaking process is performed which attaches all the anode and cathodefoil connection members together during a single, uninterrupted process.In one embodiment, the connection is performed by edge-welding at leasta portion of the distal sections of the anode foil and the cathode foiltogether. One embodiment includes a laser edge-welding process.

[0057] Alternatively, in some embodiments, a portion of the stack iswelded during a different process or by a different method than thefirst process. Some embodiments include soldering, staking, swaging,and/or applying an electrically conductive adhesive.

[0058] In one embodiment, connection members 206 and 306 are laseredge-welded to each other by a process as discussed in co-pending U.S.patent application Ser. No. 09/706,518, filed on Nov. 3, 2000, thespecification of which is incorporated herein by reference.

[0059] In one embodiment, block 606, electrically isolating portions ofthe connection members from each other, includes removing portions ofthe anode connection member and the cathode connection member. In oneembodiment, the removed portion includes where the cathode connectionmember overlays (or underlays) a portion of the anode connection member.In one embodiment, this includes removing a portion of the distalsections of the anode connection member and the cathode connectionmember. In one embodiment, electrically isolating comprises punching-outa portion of the distal section of the anode foil connection member andthe distal section of the cathode foil connection member. In oneembodiment, electrically isolating includes laser cutting a portion ofthe distal section of the anode connection member and the distal sectionof the cathode connection member.

[0060] After being processed as discussed above in block 606, proximalsections 208 of the connection members of anodes 202 are still coupledtogether and proximal sections 308 of the connection members of cathodes302 are still coupled to each other, while the anodes 202 and cathodes302 are electrically isolated from each other. Feedthroughs or otherterminal members are then used to couple the anodes and cathodes tooutside circuitry.

[0061] One aspect of the present capacitor includes a system forinterconnecting anode layers in a flat capacitor stack using vias. Inone embodiment, vias are employed to interconnect anode layers. In oneembodiment, the vias are made by inserting conductive interconnectswhich interconnect anode layers without contacting an interveningcathode layer.

[0062] For example, FIG. 7 shows a top view of a cathode and anode layerseparated by separator (for example, kraft paper). The cathode layerincludes one or more holes which provide ample clearance for aconductive interconnect. The x-section of FIG. 7, shown in FIG. 8, showsthat the conductive interconnect will interconnect anode layers withoutcontacting an intervening cathode layer. Thus, the cross section of thecathode hole exceeds that of the conductive interconnect to avoidshorting the cathode to the anodes. The conductive interconnect iselectrically connected to the anodes by welding, such as ultrasonic,resistance or other types of welding.

[0063] One way to facilitate connections is to use a masking process forconnection surfaces on the foil to ensure that the masked surfaces arenot etched and/or formed. One way to avoid mechanical breakage of thefoils is to use a masking technique which provides gradually non-etchedportions of the foil to avoid mechanical stresses (e.g. high stresspoints) due to discontinuites of etching and which provides a suitableregion for interconnection of the via to the foil. This is demonstratedby FIG. 9. The vertical lines show the cross-section of unmasked andmasked foil portions. The figure shows that foil etching graduallydiminishes over the transition from masked portion to unmasked portion.It is noted that the example shows a pure aluminum foil, but that otheretchings and foils may be masked without departing from the scope of thepresent system.

[0064]FIG. 10 shows a side view of a foil and positions of the masks forone embodiment of the present system. The top view is provided in FIG.11. The positions, shapes and sizes of the masks may vary withoutdeparting from the present system, and the demonstrated masks are shownto illustrate the system and are not intended in an exhaustive orexclusive sense. In one embodiment, thickness t is 100 micrometers.However, it is contemplated that other thicknesses may be used withoutdeparting from the present system. For example, other thicknesses,including, but not limited to, 50-600 micrometers may be used.

[0065] The foil dimensions are shown as 500×250 millimeters, but othersized foils may be employed without departing from the scope of thepresent system. In one application of the present system, a master rollof foil is masked to provide d-shaped cutouts with accurately placedmasks where the conductive interconnects are to contact the foil. In oneapplication, the spacing between foils must be large enough to provide a“web” for processing the cutouts.

[0066]FIG. 12 shows one process for providing one embodiment of acapacitor according to some of the teachings herein. Raw foil is maskedby printing the mask on the foil. The masked foil is etched and then themask is removed. Oxides are formed on the foil and it is then cut intosubrolls. The subrolls are processed by cutting shapes for the finalcapacitor out of the subrolls. The foil shapes are used to make thecapacitors.

[0067] The cathode foils are processed to accurately place the cathodeholes, which correspond to anode mask layers when overlapped. Paperseparators are also cut to provide space for the conductiveinterconnects. In one application, the perimeter of the paper is smallerthan that of the cathode to provide a nonconductive guide for theconductive interconnect. In alternate embodiments, an insulator may beused to position the conductive interconnect and to insulate againstcathode contact.

[0068] It is noted that the conductive interconnects may be connected toformed or unformed portions of the anode layer.

[0069] One way to manufacture a capacitor according to the presentteachings is to use a robotic assembly method, whereby anodes which arealready masked, etched, and formed are stacked, followed by separatormaterial, and then cathode material. In one assembly process, thecathodes are precision punched to provide accurately placed cathodeholes. The robot can use the cathode features to accurately place thecathode relative to the anodes. A separator layer and an anode layer arealso placed over the cathode using the robot. In embodiments where theconductive interconnect is a metal plug, the robot places the conductiveplug accurately prior to the placement of the separator and anodelayers. This process may be repeated to provide a stack of anodes ofmultiple layers interspersed with separator and cathode layers. Therobot can also be used to perform the welding steps.

[0070] Other types of conductive interconnects may be used withoutdeparting from the present system. For example, the conductiveinterconnects may be made of a non-circular cross section. Theconductive interconnects may be made of a suitable metal, such asaluminum. The conductive interconnects may also be made of othermaterials, including, but not limited to, conductive epoxy, conductivepolymer (such as polyimide filled with aluminum), or fused aluminumpowder. The metal used in the conductive interconnect should match theanode metal. Other anode metals/interconnect metal pairs may be usedincluding, but not limited to, tantalum, bafnium, niobium, titanium,zirconium, or combinations of these metals.

[0071] It is understood that other connections may be performed usingthe teachings provided herein. For example, it is possible to create aseries of interconnections between cathode layers using the teachingsprovided. Thus, use of the present system is not limited to anode-anodeconnections.

[0072] In one embodiment, the anode layers consist of a plurality ofanode foils. In one application is it is possible that a single anodefoil is interconnected to a triple anode foil or any multiplicity ofanode foil combinations.

[0073] In one embodiment an anode layer may include a plurality of partsand/or layers. For example, the anode layer may include two differentanode shapes in the same layer to provide a contoured edge. The shapesmay be electrically connected to provide an equipotential surface. Theuse of multiple anode parts for a single layer facilitates theconstruction of a capacitor of virtually any form factor.

[0074] Furthermore, it is possible to weld multiple anode-cathode-anodestacks at different points for different conductive interconnects in oneoperation. Additionally, depending on the welding process used, severalanode/cathode layers can be welded in a single operation.

[0075] Some of the benefits of the present system include, but are notlimited to, the following: the electrical connection system providesmechanical stability; and alignment to the stack as the layers are beingassembled; taping is not required; the assembly is ready for insertioninto the capacitor case; surface area is optimized; interior alignmentis facilitated using interior features to align the stack layer tolayer; edge-welding and/or intra-anode staking may be eliminated; and,in some embodiments, paper gluing may be eliminated.

Exemplary Embodiment of Implantable Defibrillator

[0076]FIG. 13 shows one of the many applications for capacitorsincorporating one or more teachings of the present invention: animplantable heart monitor or apparatus 700. As used herein, implantableheart monitor includes any implantable device for providing therapeuticstimulus to a heart muscle. Thus, for example, the term includespacemakers, defibrillators, cardioverters, congestive heart failuredevices, and combinations and permutations thereof.

[0077] Heart monitor 700 includes a lead system 703, which afterimplantation electrically contact strategic portions of a patient'sheart. Shown schematically are portions of monitor 700 including amonitoring circuit 702 for monitoring heart activity through one or moreof the leads of lead system 703, and a therapy circuit 701 fordelivering electrical energy through one or more of the leads to aheart. Monitor 700 also includes an energy storage component, whichincludes a battery 704 and incorporates at least one capacitor 705having one or more of the features of the exemplary capacitors describedabove.

[0078] In addition to implantable heart monitor and other cardiac rhythmmanagement devices, one or more teachings of the present invention canbe incorporated into cylindrical capacitors and/or capacitors used forphotographic flash equipment. Indeed, teachings of the invention arepertinent to any application where high-energy, high-voltage, orspace-efficient capacitors are desirable. Moreover, one or moreteachings are applicable to batteries.

Conclusion

[0079] In furtherance of the art, the inventors have devised connectionstructures and methods for interconnecting the anode foils and thecathode foils of capacitors. In one embodiment, a method includesconnecting together one or more anode connection members of one or moreanode foils and one or more cathode connection members of one or morecathode foils and electrically isolating the one or more anode foilsfrom the one or more cathode foils. Among other advantages, theexemplary method reduces the number of processing steps for constructinga capacitor.

[0080] It is understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A method comprising: connecting one or more anodeconnection members of one or more anode foils together with one or morecathode connection members of one or more cathode foils; andelectrically isolating the one or more anode foils from the one or morecathode foils.
 2. The method of claim 1, wherein electrically isolatingcomprises separating a portion of the one or more anode connectionmembers from a portion of the one or more cathode connection members. 3.The method of claim 1, wherein electrically isolating comprises removinga commonly positioned portion of each of the one or more anodeconnection members and the one or more cathode connection members. 4.The method of claim 1, wherein electrically isolating comprises lasercutting a commonly positioned portion of each of the one or more anodeconnection members and the one or more cathode connection members. 5.The method of claim 1, wherein connecting comprises connecting during acontinuous connection process.
 6. The method of claim 1, whereinconnecting comprises using an uninterrupted welding process to connectone or more edges of a distal portion of each of the one or more anodeconnection members to one or more edges of a distal portion of each ofthe one or more cathode connection members.
 7. A method comprising:positioning an anode connection member having a distal section and aproximal section and a cathode connection member having a distal sectionand a proximal section so that the distal section of the anodeconnection member overlays the distal section of the cathode connectionmember; connecting the anode connection member and the cathodeconnection member; and forming a separation in the distal section of theanode connection member and the distal section of the cathode connectionmember, wherein the proximal section of the anode connection member iselectrically isolated from the proximal section of the cathodeconnection member.
 8. The method of claim 7, wherein positioning furthercomprises positioning the anode connection member and the cathodeconnection member so that the proximal section of the anode connectionmember does not overlay the proximal section of the cathode connectionmember.
 9. The method of claim 7, wherein connecting comprisesconnecting the distal section of the anode connection member and thedistal section of the cathode connection member.
 10. The method of claim7, wherein forming a separation comprises removing a portion of thedistal section of the anode connection member and the distal section ofthe cathode connection member.
 11. The method of claim 10, whereinremoving comprises punching-out.
 12. The method of claim 10, whereinremoving comprises laser cutting.
 13. The method of claim 7, whereinconnecting comprises a continuous connection process.
 14. The method ofclaim 13, wherein the continuous connection process comprisesedge-welding at least a portion of the distal sections of the anodeconnection member and the cathode connection member together.
 15. Themethod of claim 7, wherein the anode connection member includes at leasta partially unetched portion.
 16. Foil structures for use inconstructing a capacitor, the foil structures comprising: an anode foilhaving a connection portion comprising a proximal section and a distalsection; and a cathode foil having a connection portion comprising aproximal section and a distal section; wherein the proximal section ofthe anode foil does not overlay the proximal section of the cathode foiland the distal section of the anode foil at least partially overlays thedistal section of the cathode foil when the anode foil and the cathodefoil are stacked together.
 17. The foil structures of claim 16, whereinthe connection portion of the anode foil comprises an L-shaped member.18. The foil structure of claim 17, wherein the connection portion ofthe cathode foil comprises an L-shaped member, the cathode L-shapedmember having a generally reverse image relative to the anode L-shapedmember when the anode foil and the cathode foil are stacked together.19. The foil structure of claim 16, wherein the anode connection memberincludes at least a partially unetched portion.
 20. A capacitor having acapacitor stack constructed by the method of claim
 1. 21. An implantablemedical device comprising: one or more leads for sensing electricalsignals of a patient or for applying electrical energy to the patient; amonitoring circuit for monitoring heart activity of the patient throughone or more of the leads; and a therapy circuit for deliveringelectrical energy through one or more of the leads to a heart of thepatient, wherein the therapy circuit includes one or more makingcapacitors having a capacitor stack constructed by the method ofclaim
 1. 22. A capacitor, comprising: a first anode layer; a secondanode layer; a cathode layer between the first anode layer and thesecond anode layer; a first separator layer between the first anodelayer and the cathode layer; a second separator layer between the secondanode layer and the cathode layer; and a conductive interconnect betweenthe first anode layer and the second anode layer, the conductiveinterconnect passing through a cathode hole in the cathode; wherein theconductive interconnect has a cross section which is smaller than thecathode hole and the conductive interconnect is placed to avoid directelectrical contact with the cathode layer and wherein the first anodeand the second anode are electrically connected through the conductiveinterconnect.
 23. The capacitor of claim 22, wherein the first anodelayer is substantially flat.
 24. The capacitor of claim 22, wherein theconductive interconnect is aluminum.
 25. The capacitor of claim 22,wherein the cross section is circular.
 26. The capacitor of claim 22,wherein the cross section is noncircular.
 27. The capacitor of claim 22,wherein the conduction interconnect is ultrasonically welded to thefirst anode layer and the second anode layer.
 28. The capacitor of claim22, wherein the conduction interconnect is resistance welded to thefirst anode layer and the second anode layer.
 29. The capacitor of claim22, wherein the conductive interconnect mates to an unetched region ofthe first anode layer.
 30. The capacitor of claim 22, wherein theconductive interconnect mates to an unformed region of the first anodelayer.
 31. The capacitor of claim 22, wherein the conductiveinterconnect includes a rivet.
 32. The capacitor of claim 22, whereinthe conductive interconnect includes a wire.
 33. The capacitor of claim22, wherein the conductive interconnect includes a conductive epoxy. 34.The capacitor of claim 22, wherein the conductive interconnect includesa conductive polymer.
 35. The capacitor of claim 22, wherein theconductive interconnect includes a polyimide filled with aluminum. 36.The capacitor of claim 22, wherein the conductive interconnect includesa fused aluminum powder.
 37. The capacitor of claim 22, wherein theconductive interconnect includes a conductive staple.
 38. A method,comprising: masking an anode foil; etching the anode foil; removingmasking from the anode foil, exposed unetched regions; forming oxide onthe anode foil; cutting anode shapes from the anode foil; layering afirst anode foil with a first separator layer, the first separator layerincluding first separator holes positioned approximately over theunetched regions of the first anode foil; layering a cathode foil overthe first separator layer, the cathode foil having cathode holespositioned approximately over the first separator holes; placing aconductive interconnect through each cathode hole and first separatorhole to contact an unetched region of the first anode layer; layering asecond separator layer over the cathode layer, the second separatorlayer including second separator holes positioned approximately over thecathode holes; and layering a second anode layer over the secondseparator layer, the second anode layer having its own unetched regionscontacting the conductive interconnect.
 39. The method of claim 38,wherein the conductive interconnect is a metal plug.
 40. The method ofclaim 38 wherein a robot is used for assembly.